The purpose of this work was to design ophthalmic lenses that correct peripheral refractive errors of human eyes along a meridian. We designed lenses with the tangential section of one surface based on a figured spheroid but figured in the tangential section only. The curvature of the sagittal section of this surface was adjusted separately. A merit function was used to modify these surfaces until the lenses had power errors that corrected the eye. Examples are presented of lenses that correct a schematic eye. They do excellent jobs of correcting the peripheral power errors of the eye and are relatively insensitive to small changes in fitting distance. We conclude that it is theoretically feasible to design lenses to correct peripheral refractive errors.

A hologram of a specially designed multivergence target which displays real and virtual objects (numbers) simultaneously has been used to test the vision of various spectacle corrected subjects. Through the hologram, the subjects see standard ‘60-meter’ numbers that have different amounts of blur. It is found that there is a difference between myopes and hyperopes in the amount of positive blur with which they can recognize numbers seen through the hologram and this difference is statistically significant. A similar study was then conducted in white light illumination using the ‘60-meter’ numbers of a standard test chart at 6 meter distance and positive lenses to provide the blur at the eye. This study showed no difference between the refractive groups. Our results indicate that hyperopes may be relaxing their accommodation more than myopes in viewing through the hologram.

We propose a simple method to measure the angle "α" that the visual axis (VA) makes with the optical axis of the human eye. In this method, we capture the images of the pupil from three different angles, one along the VA and the other two along angles that are symmetrical with respect to the VA. These views of the pupil are captured simultaneously by a camera in a single photograph using a pair of plane mirrors. Assuming a model eye and with the help of finite ray tracing, we compute the value of α from the measured diameters of the three images of the pupil. Having a simple means to measure the value of α can be useful for optical modeling and analysis of the human eye. Measurement of the VA may also be useful in monitoring progressive myopia.

We recently suggested the use of a holographic multivergence target to measure the spherical refractive error and the amplitude of accommodation of the human eye [K. V. Avudainayagam and C. S. Avudainayagam, Opt. Lett.28, 123 (2003)]. In this paper we report the performance of the holographic target in measuring real eyes. The holographic technique compared well with subjective refraction and autorefraction in the measurement of spherical refractive error. The performance of the holographic technique in measuring the amplitude of accommodation was similar to that of the minus lens to blur method and that of the push-up method. These results promote holography as a promising technique for testing human vision.

Lau fringes formed in the far field of a pair of gratings illuminated by spatially incoherent light are known to disappear when one grating is rotated slightly (+/-3 degrees ) with respect to the other. We observed that a cylindrical lens that was appropriately rotated could restore the high-contrast Lau fringes by bringing together the rays that are coherent with respect to each other. We have developed a new refractometer based on this phenomenon, the details of which are presented. Measurement of the cylinder power and axis of the human eye is possible with good accuracy and repeatability with this instrument.